Workers at work sites, including construction and/or mining sites, may experience dangers from several elements. For example, these sites typically include heavy machinery and equipment, such as bulldozers, cranes, front wheel loaders, soil stabilizers, rippers, and pulverizers. Operators of such heavy machinery and equipment often have a limited field of vision and may not readily detect the presence of other entities (e.g., workers, structures, and/or other machines) at the work site. The lack of knowledge regarding the presence and location of workers and other machines at the work site can lead to accidental collisions. Thus, there is a need for a system of locating and tracking the positions of workers, machines, hazardous sites, infrastructure elements, and other work site obstacles and displaying the positions of these obstacles to the machine operators.
Various systems have been proposed for tracking obstacles at work sites. U.S. Pat. No. 6,614,721 to Bokohour (“the '721 patent”) describes one example of a collision avoidance system including a reader device attached to a vehicle. The reader device periodically transmits an ultrasonic pulse. If within range of the ultrasonic pulse, a tag device, worn by a worker or positioned on a machine or obstacle, receives the ultrasonic pulse and transmits a radio frequency (RF) signal to an RF receiver associated with the reader device.
A distance between the vehicle and the worker or obstacle in the '721 patent may be determined by monitoring the elapsed time between the transmission of the ultrasonic pulse and the reception of the corresponding RF signal. While the system of the '721 patent may potentially enable tracking of entities within a certain envelope of operation, the system may suffer from several shortcomings. For example, discerning an exact position (e.g., azimuth and distance) of the tracked entity with respect to the reader may be difficult or impossible. Further, the ultrasonic waves used to monitor the distance to a tracked entity may be vulnerable to interference. The system may also be ineffective at operating in all conditions that may be present at a work site.
The present disclosure addresses one or more of the deficiencies in the prior art.